Loose Axle Nuts?!?!
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,443
Likes: 7
From: Bristol raceway area
Loose Axle Nuts?!?!
I read on the forum about some people finding loose axle nuts on '08's and earlier. Torque is 160 ft.lbs.
Checked them on our '09.
160 ft.lbs. left side.
20 ft.lbs. Right Side!? WTH?
Checked them on our '02.
160 ft.lbs left side.
40 ft.lbs. Right Side!?
There is a TSB #07-04-95-001 that addresses this "problem" but it only goes thru '08. Guess GM will have to include later models as well.
Torqued right side of '02 to 160 value but App. Monday for '09 to address this issue. Quality control?
Checked them on our '09.
160 ft.lbs. left side.
20 ft.lbs. Right Side!? WTH?
Checked them on our '02.
160 ft.lbs left side.
40 ft.lbs. Right Side!?
There is a TSB #07-04-95-001 that addresses this "problem" but it only goes thru '08. Guess GM will have to include later models as well.
Torqued right side of '02 to 160 value but App. Monday for '09 to address this issue. Quality control?
Safety Car
Joined: Jan 2008
Posts: 4,711
Likes: 3
From: Middle of No where AK
160lb is over done. You stand a good chance of snapping an axle if you decide to get in the gas. Myself and many others have gone to 100ft lb with some lock tite to help solve this issue.
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,443
Likes: 7
From: Bristol raceway area
How can you say it is overdone when The TSB states "160 lb.ft. of torque be applied to the axle nut with loctite"? I have already stated the Left axles in our cars are factory tightened to the 160 value.....
Safety Car
Joined: Aug 2006
Posts: 4,347
Likes: 25
From: Apache Junction AZ
BJK
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,443
Likes: 7
From: Bristol raceway area
Here is the TSB for anyone interested.
http://forums.corvetteforum.com/c6-c...a-warning.html
http://forums.corvetteforum.com/c6-c...a-warning.html
Last edited by Rebel 1; Nov 21, 2010 at 02:53 AM.
Racer
Joined: Apr 2006
Posts: 486
Likes: 2
From: The Villages FL
Rebel1 160 lb-ft of torque on the rear axle nut IS excessive. What is worse is to obsess about it and keep retorqueing it periodically. This practice will eventually snap the axle. Keep in mind, with fasteners one is always talking dynamic torque not static torque. If this situation really bothers you, loosen the nut and retorque to 118 lb-ft. This is the original spec. and is more than adequate. Obtain another axle nut from the dealer
P/N#10257766 and torque it to 100 lb-ft. Mark the shaft thread and the 2nd nut with a paint pen for future reference. Put the center cap back on your wheel and forget about it. I did this to my car 25k ago and everything is still AOK.
P/N#10257766 and torque it to 100 lb-ft. Mark the shaft thread and the 2nd nut with a paint pen for future reference. Put the center cap back on your wheel and forget about it. I did this to my car 25k ago and everything is still AOK.
Burning Brakes
Joined: Oct 2010
Posts: 763
Likes: 2
160 ft# is not excessive, The torque capacity for a thread that large is far in excess of that. If someone knows the actual size I'll tell you what could be "excessive" and it's likely to be something in the 300 ft# range.
Other manufacturers use shafts with indents and once the nut is tightened it is "chissled" into the indent making backing out near impossible, same could be done with these if you really wanted but I'm sure locktight would wrk fine as well.
Other manufacturers use shafts with indents and once the nut is tightened it is "chissled" into the indent making backing out near impossible, same could be done with these if you really wanted but I'm sure locktight would wrk fine as well.
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Le Mans Master
Joined: Feb 2006
Posts: 5,762
Likes: 4
From: Chandler Arizona
Take a look at the stress, 160 foot pounds of torque is very low for a 1" thread. 160 should not be a problem.
Just for grins: Here's the calculation. I don't know if the threads are exactly 1", but they are pretty close:
F= T / (.2 x d) = (160 x 12) / (.2 x 1) = 9600 pounds force
Stress = Force / Area = 9600 / .785 = 12,230 psi
The area is for a 1" diameter, it may be a little smaller, but you can see 12,230 psi is very low for a good steel shaft. It's probably under 10% of the yield strength of the material.
Now the issue is this shaft is used not only for clamping, but also for transmitting torque to the wheel. So there is a combined stress that needs to be looked at and that's probably why GM keeps the clamping force so low. However, I believe the reason these axles break is not from the combined stress, it's most likely from the impact loads of when the nut gets loose. If you have loose nuts (OK, no raunchy comments here ;0) the spline is allowed to move back and forth within the backlash causing an impact load when you nail it. As a rule of thumb, impacts can increase the loads by double.
Just for grins: Here's the calculation. I don't know if the threads are exactly 1", but they are pretty close:
F= T / (.2 x d) = (160 x 12) / (.2 x 1) = 9600 pounds force
Stress = Force / Area = 9600 / .785 = 12,230 psi
The area is for a 1" diameter, it may be a little smaller, but you can see 12,230 psi is very low for a good steel shaft. It's probably under 10% of the yield strength of the material.
Now the issue is this shaft is used not only for clamping, but also for transmitting torque to the wheel. So there is a combined stress that needs to be looked at and that's probably why GM keeps the clamping force so low. However, I believe the reason these axles break is not from the combined stress, it's most likely from the impact loads of when the nut gets loose. If you have loose nuts (OK, no raunchy comments here ;0) the spline is allowed to move back and forth within the backlash causing an impact load when you nail it. As a rule of thumb, impacts can increase the loads by double.
Last edited by glennhl; Nov 21, 2010 at 12:09 PM.
Burning Brakes
Joined: Oct 2010
Posts: 763
Likes: 2
glenhhl, I have not looked at the way GM builds their vehicles yet, but the clamping force on the rear axle is usually only effected on the wheel bearing, the actual torque transferring load is usually on a splined shaft that is in the carrier, is a corvette not like this?
Team Owner
Joined: Sep 1999
Posts: 41,732
Likes: 1,718
From: Springfield MO
I discovered that the right side axle nut was loose on my 09 Z06 at ~380 miles. Took it to the dealer, he checked it, he ordered new kit(two axle nuts and loctite), called me when the kit came in, took the car in, they replaced the nuts and kept the car 24 hours for the loctite to set, and I picked the car up. All covered under warranty. Now have 12,500 miles, and all is well.
Le Mans Master
Joined: Feb 2006
Posts: 5,762
Likes: 4
From: Chandler Arizona
Actually you quite clearly state that 160ft# is "excessive". Just accept that you erroneously made the comment with nothing but your gut and were wrong rather then trying to save face.
glenhhl, I have not looked at the way GM builds their vehicles yet, but the clamping force on the rear axle is usually only effected on the wheel bearing, the actual torque transferring load is usually on a splined shaft that is in the carrier, is a corvette not like this?
glenhhl, I have not looked at the way GM builds their vehicles yet, but the clamping force on the rear axle is usually only effected on the wheel bearing, the actual torque transferring load is usually on a splined shaft that is in the carrier, is a corvette not like this?
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,443
Likes: 7
From: Bristol raceway area
Rebel1 160 lb-ft of torque on the rear axle nut IS excessive. What is worse is to obsess about it and keep retorqueing it periodically. This practice will eventually snap the axle. Keep in mind, with fasteners one is always talking dynamic torque not static torque. If this situation really bothers you, loosen the nut and retorque to 118 lb-ft. This is the original spec. and is more than adequate. Obtain another axle nut from the dealer
P/N#10257766 and torque it to 100 lb-ft. Mark the shaft thread and the 2nd nut with a paint pen for future reference. Put the center cap back on your wheel and forget about it. I did this to my car 25k ago and everything is still AOK.
P/N#10257766 and torque it to 100 lb-ft. Mark the shaft thread and the 2nd nut with a paint pen for future reference. Put the center cap back on your wheel and forget about it. I did this to my car 25k ago and everything is still AOK.
I have match marked the nuts and axle on our '02 for future reference per your advice. The '09 goes to the dealer Monday to "fix" this "issue". Thanks
Bob
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,443
Likes: 7
From: Bristol raceway area
I discovered that the right side axle nut was loose on my 09 Z06 at ~380 miles. Took it to the dealer, he checked it, he ordered new kit(two axle nuts and loctite), called me when the kit came in, took the car in, they replaced the nuts and kept the car 24 hours for the loctite to set, and I picked the car up. All covered under warranty. Now have 12,500 miles, and all is well.
Our '09 will receive this same fix, i hope!I am taking the TSB with me to the dealer.
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,443
Likes: 7
From: Bristol raceway area
Thanks again for the advice. Bob
Racer
Joined: Apr 2006
Posts: 486
Likes: 2
From: The Villages FL
Bill took car to dealer this morning. Told service manager about issue with the axle nuts and he said "never heard of that before" . I handed him a copy of the TSB and he read it and asked me if I needed it back. Told him no and he stapled it to the service order.
Thanks again for the advice. Bob
Thanks again for the advice. Bob
Thread Starter
Drifting
Joined: Apr 2010
Posts: 1,443
Likes: 7
From: Bristol raceway area
Sure it does, and 3 months after we bought it i took it in for a trans. problem or so i thought. Had a 1-2 and 2-3 gear upshift nibble/grind when cold. Service manager said he "had never heard of that before". Vette tech said it is normal. Found CF some months later and discovered many people have this issue. Funny thing though, after some 3,000 miles or so all is well.
The deal with the "loose axle nuts" spans 9 years that i know of because our '02 had the exact same issue. Wouldn't a castle nut and a cotter pin have taken care of this years before? It worked great on the older cars. VW had a similar setup years ago. The castle axle nuts tightened to 217 lb.ft. and then a cotter pin was put in. Never any problems. Oh well.....
The deal with the "loose axle nuts" spans 9 years that i know of because our '02 had the exact same issue. Wouldn't a castle nut and a cotter pin have taken care of this years before? It worked great on the older cars. VW had a similar setup years ago. The castle axle nuts tightened to 217 lb.ft. and then a cotter pin was put in. Never any problems. Oh well.....
